Various types of motorized and manual self-stirring devices currently exist for use in the cooking of food that must be constantly stirred to avoid scorching or burning, e.g., sauces, gravies, dips, fondues, soups, puddings, etc. Most of these devices have some disadvantage which prohibits them from efficiently accomplishing their intended purpose.
For example, recipes typically require food to be transferred to and from a cooking container during the heating process. In order to transfer food using common utensils (e.g., a measuring cup, a ladle, tongs, etc.), without splattering food on a work surface or on the cook, it is important that the utensil easily fit within the opening of the container. Optimally, both the utensil and a portion of a user's hand should fit within the container opening to allow a controlled transfer of the food.
Current self-stirring cooking devices include stirring hardware mounted in a lid or on a legged bridge that extends over the container opening, between two or more portions of the container's rim. This arrangement is inconvenient when trying to transfer food, because a bridge, or lid, of the stirring device covers large portions of the container opening, thus reducing the available space within which to fit a utensil and/or hand. Quite often, the user must stop the stirring device, remove the stirring hardware from the container opening, transfer the ingredients, reposition the stirring hardware, and finally restart the stirring device. U.S. Pat. No. 3,357,685; U.S. Pat. No. 5,201,263; U.S. Pat. No. 4,832,501; U.S. Pat. No. 3,810,605; and U.S. Pat. No. 4,339,992 are examples of stirring devices having this disadvantage.
A second disadvantage seen in current self-stirring devices is poor positioning of the stirring blade. The food next to the bottom inner surface of the container is closest to the heating source and should be frequently moved to prevent the food from burning and sticking to the container. In order to move the bottom layer of food, it is very important to position the stirring blade close to the bottom inner surface of a food container. Many current stirring devices have blades positioned relatively far above the bottom inner surface of the container. This causes a layer of food to remain unstirred on the bottom of the container. Eventually, the food will overheat and burn, giving the remaining food a burned taste. Even a relatively small layer of unstirred food can produce enough burned material to destroy the taste of a dish. Examples of stirring devices having this disadvantage are described in U.S. Pat. No. 3,697,053 and U.S. Pat. No. 4,339,992.
Poor blade positioning also occurs when the vertical shaft of a stirring device and/or blades mounted on the lower end of the vertical shaft are bent or distorted. In this regard, the lower end of the blades of most stirring devices are unsupported. In watery foods, the reactive force applied to a blade mounted on a vertical shaft whose lower end is unsupported during mixing is usually inadequate to bend or distort the shaft or the blade. In contrast, the reactive force applied to a blade mounted on a vertical shaft whose lower end is unsupported when mixing rigid ingredients such as unmelted cheese or butter, can bend and distort the shaft and/or the blade. This often occurs when blades become stalled when trying to push a clump of food forward. A bent vertical shaft is undesirable because it may cause the shaft or the blade to scrape or scratch the inner surface of a container. Poorly mixed food may also result, as well as damage to the motor assembly if the vertical shaft stalls for an extended period of time. U.S. Pat. No. 4,832,501, U.S. Pat. No. 3,810,605, and U.S. Pat. No. 3,697,053 are examples of stirring devices having this disadvantage.
U.S. Pat. No. 4,854,718 discloses a manual mixer that has a cone-shaped projection on the bottom inner surface of a container about which the vertical shaft and blade is rotated. The projection helps to keep the vertical shaft from moving laterally away from its optimum position, and thus acts as a lateral support for the blade and vertical shaft. The projection, however, does not prohibit the vertical shaft from moving vertically upward during spinning. Upward movement of the vertical shaft of a stirring device results in a corresponding upward movement of blades attached to the vertical shaft, resulting in the formation of an unstirred food layer to undesirably remain on the bottom inner surface of the container. Therefore, for stirring devices used in heating food, the projection of the U.S. Pat. No. 4,854,718 does not adequately solve the problem of poor blade and/or vertical shaft positioning.
As mentioned above, poor blade positioning may also result in stalling the vertical shaft and blade. Such a stalled state is damaging to most motor assemblies, and which, if not relieved, will eventually cause the motor to fail. U.S. Pat. No. 5,013,158 discloses a self-stirring cooking device that includes an overload sensor that audibly signals to the user when the motor is being overloaded, but does nothing to protect the motor components during overload. This is a disadvantage for those cooks who may not be within audible distance of the device for a period of time.
Thus, a need exists for a new and improved self-stirring cooking device that allows the user to easily add or remove ingredients from the container using common household utensils, without having to interrupt the self-stirring device. The ideal self-stirring cooking device should have a blade that is kept at a very close distance to the bottom of the container during all types of stirring. As a part of basic design principles, the ideal device should protect its motor assembly from damage should a vertical shaft or a blade become stalled. The ideal device should also protect the user from electrical shock in the event the devices becomes immersed into conductive foods. Lastly, as with any household appliance, the entire device should be easy to assemble and disassemble, easy to clean, and easy to store.